The deployment of radio access network technologies in parallel to cellular networks, combined with the widespread use of multimode mobile communication devices, has created the opportunity to offload mobile communications to, for example, wireless access networks (such as: wireless local area networks—also known as “Wi-Fi” networks—and wireless metropolitan area networks—also known as “WiMax” networks) in order to alleviate congestion in cellular networks. These offloading techniques also enable telecommunication operators to increase their capacity and data coverage. Many wireless LANs have been deployed in airports, train stations, restaurants, hotels, libraries, campuses, etc., and their number is growing. At the same time, the data traffic going through mobile communication networks is growing as well. Efforts have been made to standardize, at least to a certain extent, cellular and wireless LANs interworking procedures, such as for example the procedures for initiating the offloading of a communication.
In that context, entities hosting an access network discovery and selection function (ANDSF) are used to provide user terminals with rules to discover and select access networks, to prioritize particular access networks and to manage the corresponding connections, so as to efficiently implement the offloading of a communication to a 3GPP or non-3GPP access network.
The ANDSF functionality is notably discussed in (i) 3GPP TS 23.402 V12.0.0 (2013-03), “Technical Specification; 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Architecture enhancements for non-3GPP accesses (Release 12)”, (hereinafter referred to as reference [1]); (ii) 3GPP TS 24.302 V12.0.0 (2013-03), “Technical Specification; 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Access to the 3GPP Evolved Packet Core (EPC) via non-3GPP access networks; Stage 3 (Release 12)” (hereinafter referred to as reference [2]); and (iii) 3GPP TS 24.312 V12.0.0 (2013-03); “Technical Specification; 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Access Network Discovery and Selection Function (ANDSF) Management Object (MO) (Release 12)” (hereinafter referred to as reference [3]), which provides details of the data that can be managed by the messages exchanged between an ANDSF and a UE. References [1], [2] and [3] are available on the 3GPP web site from the following URLs: http://www.3gpp.org/ftp/Specs/html-info/23402.htm; http://www.3gpp.org/ftp/Specs/html-info/24302.htm; and http://www.3gpp.org/ftp/Specs/html-info/24312.htm respectively.
The ANDSF contains data management and control functions to provide network discovery and selection assistance data to user terminals over the S14 interface (i.e., reference point) as per operators' policy. Two modes of operation are defined over the S14 interface for transferring access network policy information from an ANDSF to a user terminal: a “pull” mode, which allows the user terminal to fetch access network discovery and selection policies from the ANDSF, and a “push” mode, which allows the ANDSF to indicate to one or more user terminals that they should fetch policies from the ANDSF.
It is desirable to enable user terminals to connect in a convenient and secure manner to access networks, to therefore efficiently offload mobile communications to access networks such as for example Wi-Fi or WiMax.